Golf ball



Patented May 4, 1943 GOLF BALL William E. Welch, Springfield, Mass., assignor to Monsanto Chemical Company, St. corporation of Delaware No Drawing. Original a 1940, Serial No. 363,81

plication September 17,

8 Claims. This invention relates to improved plastic compositions and, more particularly, to improved plastic compositions for golf ball covers.

For certain purposes, as for example, for covers for balls and particularly for covers for golf balls, a tough, resilient material is desirable. In the past, compositions comprising mixtures of rubber and balata have been employed to a considerable extent for such purposes. however, is a relatively expensive material and, furthermore, 'is subject to oxidation and to discoloration. It is thus apparent that it is very desirable to provide compositions which are suitable for such uses as golf ball covers wherein the balata has been reduced or eliminated.

It is an object of this invention to provide improved plastic compositions comprising mixtures of rubber and polyvinyl acetal resins. It is a particular object of this invention to provide compositions comprising mixtures of rubber and Balata,

polyvinyl acetal resins which are suitable for golf J ball covers.

According to the present invention, improved compositions of matter especially suitable for golf ball covers can be prepared by mixing together rubber and a polyvinyl acetal resin in a suitable manner. If desired, these compositions may be rendered capable of subsequent vulcanization by incorporating in a suitable manner vulcanization ingredients with the other components. The resulting compositions, whether containing vulcanization ingredients or not, can be employed in any desired manner. For example, in the preparation of golf ball covers, hemispherically shaped cups may be formed in a suitable mold and thereafter molded with heat and pressure over golf ball cores.

Typical examples of the new compositions of the present invention follow, the parts being by weight.

Example 1 Parts Polyvinyl butyraldehyde acetal Pale crepe rubber -l 50 Diethyl phthalate 5 Titanium dioxide 10 The polyvinyl butyraldehyde acetal employed in this example contained substantially 17 to 21% hydroxyl groups calculated as polyvinyl alcohol, less than 3% acetate by weight and the balance acetal. This partial polyvinyl acetal was prepared by hydrolyzing polyvinyl acetate, of such a degree of polymerization that a one-molar benzene solution possessed a viscosity of substantially 25 centipoises at 20 C., and then reacting the polyvinyl alcohol thus produced with butyraldehyde by one of the well-known processes.

' The several components in this example were mixed together in a suitable manner, as for ex ample, by mixing on hot milling rolls at a front Louis, Mo., a

pplication November 1, 2. Divided and this ap- 1941, Serial No. 411,157

roll temperature of substantially 255 C. and a back roll temperature of substantially C. Generally, the rubber and pigment, for example,

titanium dioxide, were mixed together on the rolls and then the polyvinyl acetal in which had previously been incorporated the plasticizer, for example, diethyl phthalate, was mixed with the rubber-pigment mixture. The resulting composition was substantially homogeneous and was The polyvinyl butyraldehyde acetal employed in this example contained substantially 17 to 21%hydroxyl groups calculated as polyvinyl alcohol, less than 3% acetate by-weight and the balance acetal. This partial polyvinyl acetal was prepared by hydrolyzing polyvinyl acetate, of such a degree ofpolymerizatlcn that a one-molar benzene solution possessed a viscosity of substantially 55 centipoises at 20 C.,- and then react ing the polyvinyl alcohol thus produced with butyraldehyde by one'of the well-known processes.

The several components were mixed together in a suitable manner, such as that described in Example 1. In the present example, a front mixing roll temperature of substantially 260 C. and a back mixing roll temperature of substantially C. were employed. The resulting composition possessed properties similar to that of the product of Example 1.

Example 3 Parts Polyvinyl formaldehyde acetal 45 Pale crepe rubber 50 Diethyl phthalate 10 Titanium dioxide; 10 Aluminum stearate 1 The polyvinyl formaldehyde acetal employed in this example contained substantially 5 to 7% hydroxyl groups, calculated as polyvinyl alcohol, substantially 9 to 14% acetate by weight and the balance acetal. This partial polyvinyl acetal was prepared by hydrolyzing polyvinyl acetate of such a degree of polymerization that a one-molar benzene solution possessed a viscosity of sub stantially 8 centipoises at 20 C., and then reacting the polyvinyl alcohol thus produced with formaldehyde by one of the well-known processes.

The several components were mixed together in a suitable manner, such as that described in Example 1. In the present example, a front mixing roll temperature of substantially 310 C.

'ited to those given in the examples.

and a back mixing roll temperature of substantially 210 C. were employed. The aluminum stearate was mixed with the rubber at the same time that the pigment was incorporated. The product possessed properties similar to those of the product of Example 1.

While the foregoing examples all show unvulcanized compositions it is sometimes advantageous, as previously indicated, to subject the compositions to vulcanization. Thus, two batches corresponding to the following formulation were prepared in the same manner as in Example 1.

Parts Polyvinyl butyraldehyde acetal 45 Pale crepe rubber 50 Diethyl phthalate 5 Aluminum stearate 1 thi example was similar to that employed in Example 1. Into the rubber in one batch was incorporated a suitable quantity of sulphur before the other components were added, while into the rubber of the second batch a suitable quantity of a suitable vulcanization accelerator was incorporated in the same manner. Thereafter, these two batches were combined into one batch and the resulting composition subsequently vulcanized in a customary manner. This vulcanized product was found to be somewhat firmer and more homogeneous than similar unvulcanized products.

It is obvious that there are many variations that maybe introduced into the new compositions of this invention and the process of preparing the same. Particularly amenable to variation is the polyvinyl acetal resin. Thus, these acetalsmay be prepared from other vinyl ester resins than polyvinyl acetate and the degrees of polymerization of these vinyl esters are not lim- The bydroxyl, ester and acetal group contents'of these polyvinyl acetal resins may each be subjected to considerable variation. Furthermore, this invention is not limited to the particular carbonyl group-containing compounds specifically employed in the examples to acetalize the hydrolyzed polyvinyl esters. Thus, included within the scope of this invention are polyvinyl acetal resins prepared by reacting hydrolyzed polyvinyl esters with such carbonyl group-containing compounds as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, hexaldehyde, heptaldehyde, benzaldehyde, crotonaldehyde, cyclohexanone and the like and mixtures thereof.

While pale crepe rubber was employed in each of the examples, it is obvious that other types of rubber can be substituted, such as Para-rubber, smoked sheets, etc. In regard to the relative proportions of rub er and the polyvinyl acetal resins, it has been und that these proportions may be widely ried but it is generally desirable that the amount of neither of these components be less than substantially by weight of thetotal of the two components. Additional variations that may be introduced in carrying out the present-- invention include wide variation in the nature and proportion of the plasticizer mixed with the polyvinyl acetal resin, provided a homogeneous plasticized composition is produced.

Under certain circumstances it may even be ad-,

vantageous to employ the polyvinyl acetal resin without the addition of any plasticizer. Fill.

components are added on the mixing rolls is not limited to that given in the examples.

The inclusion of pigment or other coloring material in the compositions of the present invention is optional and both the nature and the amount of such materials may be widely varied.

While it is frequently advantageous to include lubricants in the mixtures, the nature and amount of such additions may be subjected to considerable variation. Other modifying materials may also be included in the compositions V. a a I 1 I The polyvinyl butyraldehyde acetal employed m of this invention w ien it is found advantageous to so do.

The new compositions of the present invention are obviously valuable for many purposes and, as previously indicated, are exceptionally well suitedfor golf ball covers. Thus, in addition to possessing resiliency, toughness, abrasion and cutting resistance, these new compositions possess the characteristic of flowing in and around the core windings of the golf balls during the molding of the covers on the cores without becoming so fluid as to flow out of the molds. Furthermore, these new compositions may be formed by other methods than molding, as for example, by extruding, calendering and the like.

This invention is limited solely by the claims attached hereto.

The present application is a division of my prior application, Serial Number 363,812, filed Nov. 1, 1940.

What is claimed is:

1. A golf ball with a cover comprising a mixture of rubber and a polyvinyl acetal resin.

2. A golf ball with a cover comprising a mixture of rubber and a partial polyvinyl acetal resin. I

3. A golf ball with a cover comprising a mixture of rubber and a partial polyvinyl acetal resin wherein neither component of said mixture is present in excess of substantially per cent by weight of the sum of the weights of the two components.

4. A golf ball with a cover comprising a mixture of rubber and a partial polyvinyl acetal resin made from a lower aliphatic aldehyde.

5. A golf ball with a molded cover comprising a mixture of substantially equal quantities of rubber and a partial polyvinyl butyraldehyde acetal resin containing substantially 17 to 21 per cent'hydroxyl groups calculated as polyvinyl alcohol, less than 3% acetate by weight and the balance acetal.

6. A golf ball with a molded cover comprising a mixture of substantially equal quantities of rubber and a partial polyvinyl formaldehyde acetal resin containing substantially 5 to 'l per cent hydroxyl groups calculated as polyvinyl alcohol, substantially 9 to 14 per cent acetate by weight and the balance acetal.

7 A golf ball with a cover comprising a mixture of rubber and a partial polyvinyl butyraldehyde acetal resin.

8. A golf ball with a cover comprising a mixture of rubber and a partial polyvinyl formaldehyde acetal resin.

\ WILLIAM E. WELCH. 

